Optimization of Fermentation Conditions for Liquid Strain of a Unique Low-temperature Straw Mushroom (Volvariella brumalis) in China

Abstract

【Objective】The Volvariella brumalis He sp.nav. is a unique low-temperature mushroom in China. The optimal conditions for the fermentation culture of liquid strains of V. brumalis were investigated, aiming to reduce the production time and costs of V. brumalis strains, and promote the standardized and large-scale production of V. brumalis.【Method】The optimal growth conditions of liquid fermentation culture of V. brumalis were studied from the aspects of carbon sources and nitrogen sources, temperature, pH, and inoculation amount. A four-factor and three-level orthogonal test was conducted to determine the best fermentation formula.【Result】The result showed that the optimal carbon source for liquid fermentation culture of V. brumalis was glucose. And the dry masses of the mycelial bulb was 1.35 g/L. The optimal nitrogen source was fermented soybean meal powder, and the dry masses of the mycelial bulb was 3.76 g/L. Suitable carbon sources (glucose, fructose) and nitrogen sources (fermented soybean meal powder, fermented corn pulp) were selected to establish L9 (34) orthogonal table for four-factor and three-level orthogonal tests to obtain the optimal formula for fermentation culture: glucose 20.0 g, fructose 10.0 g, fermented soybean meal powder 2.5 g, fermented corn syrup 2.5 g, KH2PO4 1 g, K2HPO4 0.5 g, MgSO4·7H2O 0.5 g, vitamin B1 10 mg, pH of 6-7, H2O 1000 mL. The mycelial bulb dry mass reached 5.79 g/L with this formula, and the inoculation amount was 3% when cultured at 18 ℃ and 120 r/min for 15 d. Other culture conditions were explored with an optimized formulation, obtaining an optimum temperature of 18℃, a mycelial bulb dry mass of 5.97 g/L, and an appropriate pH from 6 to 7. And when the inoculation amount reached 7%, the dry mass of the mycelial bulb was 6.31 g/L.【Conclusion】When the inoculation amount was 7%, the dry mass of the mycelial bulb was 6.31 g/L after 15 days of culture, which could be directly used in the next step of production and greatly shortened the seed production cycle of V. brumalis.

Keywords

• volvariella brumalis
• liquid fermentation
• carbon source
• nitrogen source
• orthogonal test
• formula optimization